Constant tension let-off mechanism



' D. 21, 1937. C, D BROWN 2,103,200

CONSTANT TENSION LET-OFF MECHANISM Filed March 5, 1937 2 Sheets-Sheet 1 BY :Z

ATTORNEY.

21, 1937. C D BROWN CONSTANT TENSION LET-OFF MEGHANIS-M Filed March 5, 1937 2 Sheets-Sheet 2 ATTORNEY.

Patented Dec. 2l, 1937 UNITED STATES aloazool CONSTANT TENSION LET-OFF MEcHANisM Carl D'. Brown, Hopedale, Mass., assignor to u Draper Corporation, Hopedale, Mass., a.;V corporation of Maine Application March 5', 1937', Serial fNo. 129,169 .l

'1o claims. (o1. '13s-,110)

The present invention pertains to let-off mechanisms for looms, and has more particular reference to the construction and arrangement of the whip roll structure of such mechanism and the correlation of the same with other parts of the let-off mechanism. Y Y

Mechanisms of the type mentioned' commonly include a rotatable warp beam carrying the warp supply, suitable means for controlling the rate of rotation of the warp beam, and a whip roll structure including a yielding whip roll for supporting and tensioning the warp sheet. In one commonly used form of such structure, they whip roll is depressed vertically by an increased tension of the warp sheet, and positive let-off. means is controlled from the whip roll for increasing the speed of rotation of the warp beam Whenfthe whip roll is so depressed. This prior construction is subject to the disadvantages thatV the raising' and lowering of the whip roll raises and lowers the warp sheet, and that the mechanism must include means for feeling. of the warp supply on the warp. beam and varying the operation of the let-Dif means in accordance with the diameter of such supply.

Various other let-01T mechanisms and whip roll structures have been proposed heretofore, only a few of which have been used commercially. These other mechanisms havey been objectionable in various respects which need not be herein enumerated in detail.

y I propose to provide a let-01T mechanism having a rotatable warp beam and let-olf means for controlling the rate of rotation of the warp beam as aforesaid, and a. novel whip Yroll structure which shall be so Yconstructed that it will maintain a uniform tension on the warp sheet and which shall be simple and inexpensive to construct and efficient in operation.

To the end mentioned, the invention in one of its aspects comprises a let-off mech-anism having a warp beam, let-ofi` means for controlling` the rate of rotation of the warp beam, and a whip roll structure comprising paralleli'v racks positioned above the w-arp beam a` whip roll supported by gears which roll along theracks and yielding means for so urging the whip roll longitudinally of the racks against the Warp sheet as to maintain a uniform tension thereon.

The foregoing and other objects of the invention are accomplished in the construction illus-g trated on the accompanying drawings, of which: Fig. 1 is a perspective view of a loom having the preferred embodiment of my invention applied thereto, but with certain parts removed.;

Fig. 2 isran end view of certain partsof the mechanism of Fig. 1 withthe whip roll housing in place; Y

Fig. 3 is a plan view of a partofsuch mechanism,A with the housing removed; y e i Fig. 4 is a diagrammaticgview illustrating the operation ofthe mechanism; and e Fig. 5 is a View in cross-section taken approximately'on line 5-5 of Fig. 3. j Y Y 'l'he` drawings show' only my improvedle't-o mechanism and part of a loom toL which the same has been applied, parts-of the loom not shown being ofj usual' construction forming no part of the present invention. The conventional parts that are shown include the :loom sides I, 2 which are connected by cross members such as the girt 3,. and a'bearing #which is one of Va pair of bearings fixed' to the'v loom sides and which rotatably support a Warp beam 5. The warp beam 5- includes a conventional. barrel 6 andheads 1, 8,. and contains the Warp supply from which the warp sheet is taken. The warp sheet `extends upwardlyfrom'the warp beam'at W1 and forwardly, substantially horizontally at W2 to the front of the loom', The portion W? of the warppsheet passes through a harness 9i and other usual devices not shown.. A .Y Y

The drawingsshow the preferred form of my supporting means comprising la pair of lfixed racks positioned above the warp beam, one at each side of the loom. The rack I0 consists of a series of rack teeth formed on the upper s urface of` a bracket YII which is bolted tothe left hand loom side I at I2.. The right hand rack I3 may be similarly formed andsupported; the racks being. parallel and preferably. extending horizontally forwardly and rearwardly of the loom. f

There is also shown the preferred whip roll structure, which includesa whiproll I4 yand a gear at each end thereof,V only the left hand gearY I5Y being shown. These gears are fixed to the ends of'a shaft I6 and the whip Yroll I4 is rotatably mounted on the shaft. The Vgears mesh withv and. roll along racks I0, I3, the entire whip roll structure being thus movable rectilinearly forwardly and rearwardly of the loom. The warp sheet extendsr upwardly and forwardly about the whip roll I4 and the whip roll structure is yieldingly urged rearwardly by means tobe described,

to causerthe. whip roll to bear rearwardly against f the warp sheet and tension-thel same.. It Vwill be apparentV that sinceY the racks I0,. I3 are substantially parallel tothe. forwardly extending `por- K tiQn Wfof the Warp sheet the Whip roll'structure may be rolled forwardly or rearwardly along the racks without raising or lowering the warp sheet.

The aforementioned means for urging the whip roll structure rearwardly preferably includes a sheave I1, a flexible element I8 and yielding means such-as a tension spring I9. The sheave I1 is xed to the gear I5 as by being set-screwed to the shaft I6 between the gear and the left hand end of the whip roll I4. The flexible element I8 may consist of a chain which extends about the sheave I1 and is xed thereto by a screw 20. The lower end of the spring I1 may be xed to the floor or other Asupport on which the loom rests, and the upper end of the spring is connected to one end of the element I8. These parts are so constructed and arranged that the spring pulls on the flexible elementrl in -a direction to roll the whip roll structure rearwardly along the racks. A similar sheave, flexible element and spring may be provided at the right hand side of the loom and such parts are shown at the left of Fig. l. However, the two racks I0, I3 and the gears connected by the shaft I S, will keep the whip roll in proper alignment so that two sheaves and springs are not necessary.

'I'he preferred whip roll structure and spring controlling means therefor are so constructed and arranged that the whip roll structure is gradually moved forwardly along the supporting racks as the quantity, or diameter of the warp supply on the warp beam decreases. Fig. 4 shows in full lines the position of the warp sheet and of the whip roll I4 when the warp beam is full, and in brokenV lines the positions of the warp sheet and whip roll when the warp supply is substantially exhausted. It will be apparent that as the warp supply becomes depleted the decreasing angle between the portions W1 and W2 of the warp sheet results in an increased forward pull on the whip roll even though the tension of the warp sheet remains constant. The sheave I1 is, however, a compensating sheave, that is, .the sheave is so shaped that as the whip roll structure rolls forwardly the flexible element I8 acts on an increasing radius of the sheave to thereby provide a constantly increasing resistance to the forward movement of the structure.

The compensating sheave I1 may be variously shaped to produce various predetermined relations between theforward movement of the whip roll structure and the quantity of warp supply remaining on the warp beam. The particular sheave I1 shown is so shaped that, the tension on the warp sheet and other factors remaining constant, the forward movement of the whip roll structure is directly proportional to the quantity of warp supply that has been woven off the warp beam.

The supporting means for `the whip roll, comprising rack I0 and gear I5, are enclosed by a housing 2I, Fig. 2. This housing may consist of a single casting having top end and side walls, the housing being bolted to the bracket I I at 22, 23. The housing 2I is shown in full lines on Fig. 2 but is removed in other views and its position indicated by broken lines. 'A similar housing is provided at the other side of the loom to enclose the other rack and gear, but is not shown on the drawings.

The "end wall of the housing 2| is provided with a slot 24 and a reduced extension 25 on the shaft I6 projects out through this slot. The housing and whip roll structure are provided with relatively movable indicia for visibly indicating the position of the whip roll structure on the supporting racks. In the preferred embodiment, such indicia comprise a visible mark or series of marks 26 on the housing 2| and a member 21 consisting of a collar loosely mounted on the extension and having .a pointer 28 which moves with the whip roll structure adjacent the marks 26. A rod 29 fixed in this pointer slides in a bearing 30 on the housingv 2| and prevents the collar and pointer from turning on the shaft extension 25. Where, as above described, the whip roll structure is arranged to gradually move forwardly in predetermined relation to the quantity of warp Supply on the warp beam, the marks 26 andthe pointer 28 indicate at a glance the approximate quantity of warp remaining on the warp beam. Furthermore, the tension on the warp sheet may be determined merely by comparing the quantity of warp on the warp beam with the quantity indicated by the marks and pointer. This method of determining warp tension is at least as accurate as the prior practice of pushing on the warp sheet with the hand, and prevents soiling or other damage to the warp which was caused by such prior practice.

In accordance with some aspects of my invention, the character of the let-off means for controlling the rate of rotation of the warp beam is not material. The drawings show onegood form of positive let-off means, wherein a shaft 3l is geared to the beam head 1 by a pinion, not shown, and the shaft 3| is positively rotated by a worm 32 which drives a worm gear 33 on such shaft. The worm 32 is fixed on a shaft 34 which revolves in bearings in a bracket 35 xed to the loom side I. A ratchet wheel 36 is fixed to the shaft 34. A pawl carrier 31, having pawls 38, oscillates on lthe shaft 34. A rod 39, pivoted to the pawl carrier is pulled forwardly by a reciprocating link 40 to thereby rotate the ratchet wheel and shaft 34 in the direction to effect let-off of the warpsheet from the warp beam. The return stroke of the rod 39 and pawlcarrier 31 is effected by a compression spring 4I.

The positive let-off means shown, vas thus far described, is similar to the corresponding parts of the Bartlett let-olf which is well-known in the art. I have, however, provided a novel means for controlling the let-off means, to vary the speed of rotation of the warp beam in accordance with the position of the Whip roll structure on its supporting means. The preferred form of such means comprises a link 42 and lever 43. The link has a head provided with a slot 44 in which the end of the extension 25 of the shaft IB slides. The other end of this link is pivoted at 45 to the upper end of the lever 43. The lever 43 is pivoted intermediate its ends on a stud 46 carried by the loom side I. The lower end of the lever has an apertured head 41 which embraces the rod 39. A spring 48 pulls the lower end of the lever 43 forwardly to a position determined by engagement of the forward end of the slot 44 with the extension 25. A collar 49 isV fixed to the rod 39 and engages the head V41 to limit rearward movement of the rod by spring 4I. The Spring 48 is appreciably stronger than the spring 4I.

It will be apparent that when the whip roll structure is at its rearwardmost position on the supporting racks I0, I3, the head 41 will be at its forwardmost position. This results in the rod 39 being held from movi-ng very far rearwardly and, since the link 4U always moves forwardly to a predetermined position, the stroke of the rod 39 and pawl carrier 3-'l will be relatively short. Then as the whip roll structure moves forwardly, the headv 4l will bemoved rearwardly and the length of stroke of the pawl carrier correspond-V ingly increased, to thereby increase the speed of rotation of the warp beam.

Thev mechanism just described will serve to vary the speed of rotation of the warp beam whenever, in the operation of the loom, the whip roll structure is moved ahead or back of the position whichrit should occupy relative tothe diameter of the warp supply remaining on" the warp beam. Thus, the construction is such-that the let-off mechanism need not be adjusted to take upk or let off the warp sheet when the cloth takeup (not shown) is manipulated after a pick out, because the whip roll structure will move to maintain tension on the warp sheet and the speed of rotation ofv the warp beam will be automatically.

varied thereby. This variation in the speed of rotation of the warp beam as a result of aY temporary change in the position of the whip roll structure will, of course, result in the whip roll structure. promptly returning to its proper predetermined position.

A further important feature of the preferred embodiment of the invention isthat, in this con-v struction the speed of rotation of the warpi beam is automatically increased as the warp supply becomes depleted. The parts shown are so de signed that as the whiproll structure moves forwardly on its supporting racks the speed of rotation of the warp beam is increased at the proper rate (within the limitations of a pawl-andratchet drive) to compensate for the decrease in diameter of the warp supply. In this way Ihave eliminated any necessity for manual adjustment of the let-01T and have eliminated the above mentioned means for feeling of the warp supply, which were required in prior let-off mechanisms.

Having fully disclosed the preferred emb-odiment of my invention, I claim:

1. In a let-off mechanism for looms, the combination of a rotatable warp beam, supporting means comprising a pair of spaced parallel racks positioned above said warp beam and extending generally forwardly and rearwardly of the loom, a whip roll structure including gears meshing with and rolling along said racks, and a whip roll supported by said gears for movement therewith along with said racks, the warp sheet from said warp beam extending upwardly an-d forwardly `about said whip roll, means yieldingly urging said whip roll rearwardly along said racks to tension the warp sheet, and let-off means for controlling the rate of rotation of said warp beam.

2. In a let-off mechanism for looms, the combination of a rotatable warp beam, supporting means comprising a rack at each side of the loom above said warp beam, said racks being parallel, a whip roll structure including a whip roll and a gear at each end of said whip roll, said gears meshing with and rolling along said racks, the warp sheet from said warp beam extending upwardly and forwardly about said whip roll,a sheave xed to one of said gears, a exible element extending about and xed to said sheave, yielding means connected to said element and pulling the same in a direction to urge said whip roll against the warp sheet, and let-off means for controlling the rate of rotation of said warp beam.

3. In a let-off mechanism for looms, the combination of a rotatable warp beam, supporting meansv comprisingv parallel racks positioned one aty each sidel ofthe loom above said warp beam,

a.' whip roll Vstructure adapted to move longitudi nally of said, racks, said structure comprising a. Whip roll' and av gear at each end of said whip roll, saidr gears meshing with and rolling along said racks, thev warp sheet from said warp beam extending upwardly and forwardly about said whiproll, a compensating sheave fixed to one vof said gears, alexible element extending about andA xedv to said sheave, yielding means connected to said element and pulling' the same in a direction to urge said whip roll against the Warp sheet and left-off means for controlling the rate of rotation of said warp beam.

4'. In aA let-oifrmechanism for looms, the combination of a rotatable warp beam, supporting means comprising a rack. at each side of the loom above said warp beam, said racks being parallel and extending generally forwardly and rearwardly of the loom, a whip roll structure including gears meshing with and rolling along said racks and a whip roll supported by said gears, the warp sheet extendingV from said warp beam upwardly and forwardly about said whip roll andA thence forwardly to the Yfront of the loom, a compensating sheave fixed to one of said gears, a flexible element extending about and fixed to said sheave, yielding means pulling on said element ina direction to urge said` whip roll rearwardly along said racks to vthereby tension the warp sheet, and means for controlling the rate of rotation of said warp beam.

5. In a let-olf mechanism for looms, thecombination of a rotatable warp beam, supporting means comprising a rack at each side of the loom above saidwarp beam, said racks being parallel, a whip roll structure including a whip roll and aI gear at each end of said whip roll, said gears.Y

meshing with and rolling along said racks, means controlling said whip roll structure so that the latter is gradually rolled forwardly along said racks in predetermined relation rto the quantity of warp supply on said warp beam, a. housing enclosing each of said gears and racks, and indicia comprising a mark on one of said housings and a member carried by said structure and moving adjacent said mark to indicate the position of said structure on said racks'.

6. In a let-off mechanism for looms, the combination of a rotatable warp beam, supporting said shaft, said gears meshing with and rollingV along said racks, the warp sheet rfrom said warp beam extending upwardly andY forwardly about said whip roll, a compensating sheave fixed on said shaft, a flexible element extending about, and xed to said sheave, yielding means pulling on said element in a direction to urge said whip roll against said warp sheet, and let-off means for controlling the rate of rotation of said warp beam.

7. In a let-off mechanism for looms, the combination, of a rotatable warp beam, supporting means comprising a rack at each side of the loom above said warp beam, said racks being parallel and extending generally forwardly and rearwardly of the loom, a whip roll structure including a shaft having a fixed gear at each end thereof and a whip roll rotatably mounted on said shaft, said gears meshing with and rolling along said racks, the warp sheet from said warp beam extending upwardly and forwardly about said whip roll and thence forwardly to the front of the loom, a compensating sheave fixed on said shaft, a exible element extending about and fixed to said sheave, yielding means pulling on said element in a direction to urge said whip roll rearwardly against the warp sheet, said yielding means and said sheave being constructed and arranged to provide a constantly increasing resistance to forward movement of the whip roll as the warp supply on said warp beam becomes depleted, and means for controlling the rate of rotation of said warp beam.

8. In a let-off mechanism for looms, the combination of a rotatable warp beam, supports comprising xed racks positioned one at each side of the loom above said warp beam, said racks being parallel and extending generally forwardly and rearwardly of the loom, a whip roll structure including a shaft having a xed gear at each end thereof and a whip roll rotatably mounted on said shaft, said gears meshing with and rolling on said racks, the warp sheet from said warp beam extending upwardly and forwardly about said whip roll and thence forwardly substantially parallel to said racks, means yieldingly urging said whip roll structure rearwardly to thereby tension the warp sheet, said means and said structure being so constructed and arranged that said structure is gradually moved forwardly along said racks as the Warp supply on said warp beam becomes depleted, and let-off means controlled by said Whip roll structure for varying the speed of the rotation of said warp beam in accordance with the position of said structure on said racks.

9. In a let-oir mechanism for looms, the combination of a rotatable warp beam, supports comprising Xed racks positioned one at each side of the loom above said warp beam, said racks being parallel and extending generally forwardly and rearwardly of the loom, a warp tensioning whip roll structure supported by said racks and constructed Yand arranged to be gradually moved forwardly on said racks by the warp sheet as the warp supply on said warp beam becomes depleted, said structure including a shaft having a fixed gear at each end thereof and a whip roll rotatably mounted on said shaft, said gears meshing with and rolling on said racks, means yieldingly opposing said forward movement of said structure, and let-off means controlled by said structure for varying the speed of rotation of said warp beam in accordance with the position of said structure on said racks.

l0. In a let-off mechanism for looms, the combination of a rotatable warp beam, supports comprising xed racks positioned one at each side of the loom above said warp beam, said racks being parallel and extending generally forwardly and rearwardly of the loom, a warp tensioning whip roll structure supported by said racks and constructed and arranged to be gradually moved forwardly on said racks by the warp sheet in predetermined relation to the diameter of the warp supply on said warp beam, said structure including a shaft having a xed gear at each end thereof and a whip roll on said shaft, said gears meshing with and rolling on said racks, means acting 

